Would you give up your car if you could share one instead? How a hot concept could ease gridlock

Grace Kim refuses to own a car. But at least once a month, the Seattle architect drives 30 miles to the suburbs to visit her mother. If she's in the mood, she'll cruise out to the airport to pick up friends. Occasionally, she wants a car to lug home groceries in bulk or try a new restaurant across town. And when clients need to visit a building site, Kim is at the wheel.

All that's possible because Kim and her husband, architect Michael Mariano, are members of Flexcar, one of more than a dozen car-sharing companies revving up across the U.S....